1. Field of the Invention
The present invention relates to an organic light emitting display (OLED) device and a method of fabricating the same, and more particularly, to an OLED device having an improved sealing structure and a method of fabricating the same.
2. Description of the Related Technology
FIG. 1 is a plan view of a conventional organic light emitting display (OLED) device. The OLED device 50 includes a pixel region 60 and a non-pixel region surrounding the pixel region. The pixel region 60 includes a plurality of pixels (not shown). The non-pixel region includes a common power supply (Vdd) line 130, a driving integrated circuit 70, a second electrode power supply line 135, and a sealant 160.
The common power supply line 130 is arranged on top and both sides of the pixel region 60, as shown in FIG. 1. The common power supply line 130 is used to supply a voltage to circuits in the pixel region.
The driving integrated circuit (IC) 70 includes a data driver (not shown) and a scan driver (not shown). The data driver is configured to output a data signal to drive the pixels in the pixel region 60. The scan driver is configured to output a selection signal to the pixels in the pixel region 60.
The second electrode power supply line 135 is disposed on one side of the pixel region 60. The second electrode power supply line 135 is connected to a second electrode (not shown) disposed over the second electrode power supply line 135. The second electrode power supply line 135 receives a second electrode voltage from an external terminal and applies the second electrode voltage to the second electrode through a contact hole (not shown).
The sealant 160 surrounds the pixel region 60 and overlaps with the common power supply (Vdd) line 130. The sealant 160 attaches upper and lower substrates to each other.
In the conventional OLED device 50 described above, when the scan driver of the driving IC 70 transmits the selection signal to the pixel region 60, the data driver of the driving IC 70 transmits the data signal to the pixel region 60, the common power supply (Vdd) line 130 applies the power supply voltage, and the second electrode power supply line 135 applies the second electrode voltage to the second electrode, a switching transistor (not shown) and a driving transistor (not shown) of each of pixels arranged in the pixel region 60 are driven so that an organic light emitting diode (not shown) emits light.
FIG. 2 is a cross-sectional view taken along the line I-I of FIG. 1, which illustrates the sealant structure of the conventional OLED device. Referring to FIG. 2, the conventional OLED device includes a substrate 100 having a pixel region 60 and a non-pixel region b. A gate insulating layer 110 is formed on the surface of the substrate 100.
Also, an interlayer insulating layer 120 is formed on the surface of the gate insulating layer 110. The interlayer insulating layer 120 may include a silicon oxide (SiO2) layer, a silicon nitride (SiNx) layer, or both layers stacked over each other. In one embodiment, the silicon oxide (SiO2) layer and the silicon nitride (SiNx) layer may be stacked separately. For example, a first interlayer insulating layer 120a may be formed by stacking a silicon oxide (SiO2) layer over the gate insulating layer 110 and annealing the silicon oxide (SiO2) layer at a temperature of about 430° C. for about four hours. A second interlayer insulating layer 120b may be formed by stacking a silicon nitride (SiNx) layer over the silicon oxide layer and hydrogenating the silicon nitride (SiNx) layer at a temperature of about 380° C.
Thereafter, a common power supply (Vdd) line 130 is formed on the interlayer insulating layer 120 in the non-pixel region b. The common power supply (Vdd) line 130 may be formed of the same material as source and drain electrodes (not shown) of the OLED. For example, the common power supply (Vdd) line 130 may be formed of one selected from the group consisting of molybdenum (Mo), tungsten (W), tungsten molybdenum (MoW), tungsten silicide (WSi2), molybdenum silicide (MoSi2), and aluminum (Al).
Thereafter, a planarization layer 140 is formed on the common power supply (Vdd) line 130. The planarization layer 140 is typically formed of one organic material selected from the group consisting of polyimide (PI), polyamide (PA), acryl resin, benzocyclobutene (BCB), and phenol resin.
In addition, a sealing portion is formed on an upper sealing substrate (not shown), and a sealant 160 is formed in the sealing portion. There is a vacancy on one side of the sealant 160 over the planarization layer 140. The vacancy may be filled with fillers. In one embodiment, the sealant 160 may be formed of a material that is curable by ultraviolet (UV) light or heat.
Upper and lower insulating substrates are bonded to each other so that the pixel region 60 formed on the lower substrate is protected from external moisture and gases. In this case, the sealant 160 is attached onto a portion of the planarization layer 140 over the common power supply (Vdd) line 130.
However, in this case, since the sealant 160 is an organic polymer that is in a liquid or plastic phase, the sealant 160 is very likely to spread when the substrates are pressed against each other. In other words, when the upper and lower substrates are brought into contact with each other, a physical force is applied to the sealant 160. This may cause the sealant 160 to spread into devices (not shown) formed in the pixel region 60. In this case, the devices formed in the pixel region 60 may sustain damages due to the sealant 160.
In addition, in the above-described sealing structure, the adhesion between the organic planarization layer 140 and the sealant 160 is unreliable. Thus, moisture or impurities may permeate into the pixel region 60 from outside, and thus may damage the devices in the pixel region, adversely affecting the reliability of the product. Therefore, there is a need to provide a sealing structure to prevent these problems.